During the rotary drilling operation, a rotary drill bit would be inserted into the formations within the earth to provide a well bore. This bore would eventually lead to the sedimentary formations which may contain oil or natural gas. The drill bore would then be cased within metal sheathing, with large pipes or the like, and the cuttings would be removed from the hole and carried up by use of various weights of drilling mud. The drilling mud utilized in this process would be processed out of the bore where it would be distributed across various shale shakers, desanders and desilters and other piees of equipment for further processing in order to help eliminate unfavorable impurities in the drilling mud. During the drilling process, the cuttings which are brought up from the bore, are usually saturated with water and following their passage through a shale shaker which utilizes a certain size mesh screen, this drilling mud would then flow to desanders and desilters which would help to remove the impurities from the drilling mud.
Following the removal of the impurities from the drilling mud, the mud then would be recirculated back into the hole in order to help remove the cuttings from the drill bit during the drilling process, and to help reduce the possibility of a blow-out occurring by providing weight above any potential oil or gas bearing formations. In the present state of the art, the cuttings which have been passed through various stages are discharged into normally a drilling reserve pit on land and off-shore would normally be discharged into the water or in some instances, onto a barge for transport to a land disposal area. On barge locations, cuttings would be stored for transportation to a land area disposal site where they can be disposed of under certain guidelines. When the cuttings are brought to the surface with the drilling mud, the drilling mud and the cuttings would absorb a substantial amount of moisture and/or oil.
The most troublesome problems which arise are areas where the drilling operations take place on land, and there is sufficient population for creating a health hazard and a potential risk for unauthorized personnel to wander on to the location area. The clean up of these locations becomes a very serious problem during and after the drilling operation, and oil companies undergo normally tremendous expense in these operations. The excess cuttings, often times must be hauled off by large trucks which is a very expensive process, and alternative methods are required in order to reduce the cost and time involved in the disposal of these cuttings. Likewise, on off-shore operations, the drill cuttings, ifthey contain a portion of oil, cannot be dumped into the water around the rig, thus must be hauled off to land where they may be disposed of in storage pits and likewise, alternative methods of disposal would be necessary in order to cut the cost and the time involved.
Several patents speak to the treatment of cuttings and/or drilling mud from drill holes, and these, for the most part, are as follows:
U.S. Pat. No. 3,693,951 issued to Lawhon et al entitled "Process and Apparatus for the Treatment of Well Cuttings" which teach the use of a heating chamber having a conveyor to take drilling mud through the chamber for treatment. Essentially, a pre-heater for partial drying in a high intensity heater for the complete drying of the cuttings is provided. Also, there is a disclosure of the process for treating by a pair of heating steps, including conveying the cuttings to a combustion chamber and resolving the cuttings while intermediate of the combustion chamber for later discharge.
U.S. Pat. No. 3,293,768 issued to A. D. Blank et al entitled "Treating Fluidized Material" would teach the use of an apparatus which would utilize up-flowing gas and down-flowing gas to centrally dry material that is being conveyed through the apparatus. The solid material would move along a continuous belt, with gas flowing upward to support and lift and fluidize material in the stream of gas and would have a down-flowing stream of air for in turn, redepositing the material on the bed with a kind of tumbling of the material within the fluidized chamber as it is dried.
U.S. Pat. No. 2,678,504 issued to W. A. Knopp, entitled "Apparatus for Drying Cut Staples" is adapted for fiber drying in a mat or blanket type conveyor belt which passes through a heated chamber.
U.S. Pat. No. 4,139,462 issued to Sample, Jr. entitled "Method for Thermally Treating Oil Well Cuttings" would teach the use of drying drill cuttings by utilizing continuous process employing the principal of stream stripping distillation to affect the simultaneous removal of hydrocarbons and water from the cuttings, leaving them in a condition sufficiently pollution free as to be fit for direct disposal in waters adjacent to the off-shore drilling platform. The cuttings would pass through the heated vessel at about 500.degree. to 700.degree. F. for a period of 5-15 minutes and then would be discharged from the bottom of the vessel. During the process, it must be oxygen free so that the ignition of the cuttings does not occur.
U.S. Pat. No. 3,713,499 issued to Arscott et al entitled "Method and Apparatus for Treating Drilling Mud," and U.S. Pat. No. 3,777,405 issued to Crawford entitled "Drilling Mud Reclaiming Apparatus" are also several patents which teach methods of drying and treating drill mud.